E.8 Geographical Identifier

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

The Geographical Identifier identifies a geographical area within a country or territory. It may be described in a geospatial manner (e.g. geodetic coordinates) within a country or territory or as civic user location information (e.g. a postcode, area code, etc.), or use an operator-specific format. It is assumed that a given cell cannot belong to more that one area identified by a Geographical Identifier.

A network which requires the Geographical Identifier to be generated in the IMS may implement a mapping table between an (E)CGI (received as part of Access Network Information) and a Geographical Identifier. The P-CSCF or an IMS AS may then, based on operator policy, use this mapping table to convert the user location into a Geographical Identifier, and insert the Geographical Identifier in the SIP signalling, thus enabling routing decision in downstream IMS entities or interconnected network.